The Final Fate of the Rolling Tachyon

摘要

We propose an alternative interpretation of the boundary state for therolling tachyon, which may depict the time evolution of unstable D-branes instring theory. Splitting the string variable in the temporal direction into theclassical part, which we may call "time" and the quantum one, we observe thetime dependent behaviour of the boundary. Using the fermion representation ofthe rolling tachyon boundary state, we show that the boundary state correctlydescribes the time-dependent decay process of the unstable D-brane into aS-brane at the classical level.